1. Technical Field
The present disclosure relates to surgical fastener applying apparatus and, more particularly, to surgical fastener applying apparatus that include a deflection control system for controlling and/or reducing the rate of deflection of an anvil beam.
2. Background of Related Art
Surgical fastener applying apparatus, for example, surgical stapling apparatus, have been developed in which a staple cartridge receiving half-section including a staple cartridge assembly provided at a distal end thereof, is operatively connected (e.g., pivotably connected) to an anvil half-section including an anvil provided at a distal end thereof. The staple cartridge assembly preferably includes a plurality of surgical staples which are ejectable therefrom. The staple cartridge assembly may be manufactured as an integral part of the staple cartridge receiving half-section, or the staple cartridge assembly may be designed and manufactured as a disposable loading unit for use in a reusable surgical stapling apparatus.
Typically, when the distal end of the staple cartridge receiving half-section is approximated toward the distal end of the anvil half-section, to clamp tissue inserted therebetween in preparation for stapling, the opposing surfaces of the distal end of the staple cartridge assembly and the distal end of the anvil assembly are spaced apart by a predetermined distance which is pre-established and fixed for each surgical stapling apparatus. This spacing is sometimes referred to as the “tissue gap” of the surgical stapling apparatus.
Since it is desirable that the “tissue gap” be substantially uniform and/or “fixed” (i.e., having the same dimension throughout the stapling operation), in order to form lines of uniform staples along the cartridge, the operator of the surgical stapling apparatus needs to ascertain whether the “tissue gap” is loaded with more or thicker tissue than recommended (i.e., overloaded) which may result in undesired or increased deflection of the distal end of the anvil half-section and/or the staple cartridge receiving half-section. As used herein, the term “deflection” is understood to include flexing, bending, deforming, biasing, skewing and the like.
It is desirable that tissue having a thickness larger, preferably slightly larger, than the height of the “tissue gap” be clamped between the tissue contacting surface of the staple cartridge assembly and the anvil so that when the surgical stapling apparatus is clamped onto the tissue, the tissue substantially fills the entire height of the “tissue gap”. However, it has been noticed that clamping of such tissue between the tissue contacting surfaces of the distal ends of the anvil and staple cartridge receiving half-sections tends to cause the distal ends of the anvil and/or staple cartridge receiving half-sections to deflect. The greater the initial and/or resultant thickness of tissue clamped between the distal ends of the staple cartridge receiving and anvil half-section, especially adjacent and at their distal tips, the greater the degree of deflection of the distal end of the anvil half-section and/or the staple cartridge receiving half-section.
In the past, the deflection at the distal end of the anvil half-section was reduced and/or eliminated by using a relatively heavier construction (i.e., thicker structural elements), a relatively larger construction or relatively stronger materials. These approaches increase the size and/or cost of the surgical stapling apparatus.
It would be desirable to provide a surgical stapling apparatus that includes a deflection control system for controlling and/or reducing the rate and/or degree of deflection of the distal end of the anvil half-section when tissue is clamped between the distal ends of the anvil and staple cartridge receiving half-sections.
It would also be desirable to provide a surgical stapling apparatus that has a deflection control system which allows rapid initial deflection of the distal end of the anvil half-section to a specific value and which thereafter causes a decrease or reduction in the rate and/or degree of deflection in a predetermined manner.
It would also be desirable to provide a surgical stapling apparatus that includes a deflection control system which allows rapid initial deflection of the distal end of the anvil half-section to efficaciously achieve the optimal tissue gap when clamping relatively thin tissue and which thereafter reduces the rate of deflection in relatively thicker tissue to maintain the tissue gap as close as possible to the optimal tissue gap.
Surgical stapling apparatus constructed in this manner would allow for rapid deflection of the distal end of the anvil half-section to a specific value followed by a decrease in the rate of deflection of the same. Accordingly, the distal end of the anvil half-section is able to deflect quickly to the optimal tissue gap in relatively thin tissue and deflect slowly in relatively thicker tissue to remain as close as possible to the optimal tissue gap.